Law of Supply: The Producer Side
Quality reviewed September 2026
- Grades
- Grades 9-12
- Time
- About two 50-minute class periods
- Includes
- 11 ready-to-teach files
- Format
- Word (.docx) · PowerPoint (.pptx)
- Slide deck
- Guided notes
- Guided notes teacher key
- Activity + answer key
- Quiz + answer key
- Exit ticket + answer key
- Teacher guide
- Teacher presentation notes
What students do
- Read a supply schedule and supply curve for Bella's Pizza Kitchen to predict quantity supplied at four different prices
- Distinguish a movement along the supply curve from the two reasons behind it, the profit motive and rising marginal cost
- Explain why the 800th pizza costs more to make than the 200th, using the concept of marginal cost
- Apply the ceteris paribus assumption to determine what a price change does and does not do to the supply curve
What it covers
- The two reasons producers offer more at a higher price, the profit motive and rising marginal cost
- How a supply schedule and a supply curve show the exact same information as a table and a graph
- The difference between supply, the whole curve, and quantity supplied, one point on it
Learning targets
- State the LAW OF SUPPLY (price up = quantity supplied up, all else equal) and read an upward-sloping supply curve and the supply schedule behind it
- Distinguish a MOVEMENT ALONG the supply curve (caused only by a price change) from the two reasons price drives quantity supplied - the PROFIT MOTIVE and RISING PRODUCTION COSTS
- Use a real supply schedule and supply curve to predict how quantity supplied changes when price changes, and explain WHY a higher price must cover the rising cost of producing more
Peek inside
The Rule in One Sentence
When price goes UP, quantity supplied goes .
When price goes DOWN, quantity supplied goes .
Price and quantity supplied move in the direction.
Same direction = a relationship.
You Already Live This
1. Marcus says his whole job runs on one rule: all else equal, when the market price of pizza rises, Bella's offers more pizzas, and when the price falls, Bella's offers fewer. The rule that price and quantity supplied move in the same direction is the of .
Why this matters
Raising a price does not just hand the seller more money, it pulls more pizzas into existence, and Bella's Pizza Kitchen is small enough to watch that happen pie by pie. Her supply schedule shows the 800th pizza tonight costs more to make than the 200th did.
The assumption that trips up almost every class is that the cost of one more unit stays flat no matter how many you have already made, which is exactly why that 800th pizza catches them off guard. Naming rising marginal cost alongside the plain profit motive as the two reasons supply rises is a concept most economics classes rush past.
From one teacher to another
Students who found the buyer side of demand clear can slide straight into this one, the deliberate producer-side twin I built to run parallel to it. The activity keeps circling back to the two reasons a higher price pulls out more supply, the profit motive and rising marginal cost, because that's where classes actually get stuck. I like that a kid who's never run a business still walks away knowing why the 800th pizza costs more to make than the 200th.
Every file in this toolkit
-
Activity (Student)
Marcus Reyes has students read Bella's Pizza Kitchen supply numbers, 200 pizzas at $4 up to 800 at $16, then split the profit motive from rising marginal cost before naming a movement along the curve.
-
Activity (Answer Key)
Answer key math splits profit motive, the extra profit per pizza, from rising marginal cost, the pricier 800th pie, then sorts four scenarios like an oven upgrade or a cheese price spike into movement along the curve or a full shift.
-
Exit Ticket (Student)
Corn jumping from $4 to $7 a bushel sets up one question on quantity supplied, another names the reason a bakery bakes more cakes at a higher price, and a third traces what a rising own-price does to the supply curve. A producer choice gets tied to one named reason.
-
Exit Ticket (Answer Key)
Quantity supplied rising after the corn-price jump is the first answer, the profit motive explains the bakery's extra cakes, and a slide along that same curve is what a rising own-price produces. Full credit needs both the profit motive and marginal cost explained correctly.
-
Guided Notes (Student)
Blanks walk a pizza shop's own schedule, 200 pizzas at $4, 600 at $12, and 800 at sixteen, before naming the two forces, profit and rising marginal cost, that bend the curve upward.
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Guided Notes (Teacher Key)
Answer blanks complete the schedule end to end, price on the vertical axis and quantity on the horizontal, with figures at 200, 600, and 800 pizzas plus definitions for movement along the curve versus a shift and for ceteris paribus.
-
Quiz (Student)
A pizza shop's supply schedule sets up items that read quantity supplied at four prices, name the axis for price on the curve, and separate a movement along it from a shift.
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Quiz (Answer Key)
Quantity supplied rising with price confirms a direct relationship, and the answers link a steeper marginal cost to why making extra pizzas past 200 gets pricier, then separate a movement along the curve from a shift.
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Slides
A supply schedule and curve open the deck, higher price meaning higher quantity supplied, before two forces get named for why, chasing profit, and rising cost per additional pizza at Bella's. Ceteris paribus and movement along the curve versus a full shift close the vocabulary slides.
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Teacher Guide
Pizza counts from 200 to 800 on a schedule structure the warm-up, and discussion prompts separate supply from quantity supplied before students design their own schedule for a business they know.
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Teacher Presentation Notes
A lemonade stand charging $5 instead of $1 opens the discussion before the numbers turn concrete. The script then pairs a supply table, 200 pizzas at $4 climbing to 800 at $16, with sneaker resale and oil drilling as two more places the same rule shows up.
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